EP 295 217 A and EP 352 944 A describe a class of 1-N-arylpyrazole-based insecticides. A particular compound of this class is 5-amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((trifluoromethyl)sulfinyl)-1H-pyrazole-3-carbonitrile, also known as Fipronil. Fipronil has proven to be particularly effective as a parasiticide against crop parasites and against mammal ectoparasites, in particular fleas, ticks, flies and myiases.
Fipronil formulations are disclosed in GB 2 331 242 A, which also discloses the combination of Fipronil with other parasiticides. Furthermore, GB 2 317 264 A discloses Fipronil formulations additionally comprising an IGR (insect growth regulator) compound, e.g. Methoprene.
Parasiticidal formulations comprising Fipronil are marketed for use in the home treatment of domestic pets, e.g. cats and dogs. One such formulation is FRONTLINE® PLUS FOR DOGS.
However, a problem with these known formulations is their relatively low flashpoints, i.e. the lowest temperatures at which they can form an ignitable mixture in air. The Material Safety Data Sheet for the FRONTLINE® PLUS FOR DOGS formulation indicates the flashpoint for this formulation to be 36° C. (97° F.).
A liquid which forms an ignitable mixture at 36° C. presents a safety risk during use in the home, and during manufacture, distribution and storage, because temperatures in many countries exceed this level during summer. There is therefore a need for effective parasiticidal formulations comprising Fipronil which have higher flashpoints, and therefore improved safety profiles, but which still retain parasiticidal efficacy.
Accordingly, the object of the present invention is to provide a parasiticidal formulation comprising Fipronil having improved safety while maintaining parasiticidal efficacy.